[PATCH] kvm: vmx: Raise #UD on unsupported RDSEED

[PATCH] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

A guest may not be configured to support RDSEED, even when the host
does. If the guest does not support RDSEED, intercept the instruction
and synthesize #UD.
---
 arch/x86/kvm/vmx.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ed1074e98b8e..8b9015f081b7 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 			SECONDARY_EXEC_SHADOW_VMCS |
 			SECONDARY_EXEC_XSAVES |
+			SECONDARY_EXEC_RDSEED_EXITING |
 			SECONDARY_EXEC_ENABLE_PML |
 			SECONDARY_EXEC_TSC_SCALING |
 			SECONDARY_EXEC_ENABLE_VMFUNC;
@@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 	if (!enable_pml)
 		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
 
+	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
+		exec_control &= ~SECONDARY_EXEC_RDSEED_EXITING;
+
 	return exec_control;
 }
 
@@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
 	return handle_nop(vcpu);
 }
 
+static int handle_invalid_op(struct kvm_vcpu *vcpu)
+{
+	kvm_queue_exception(vcpu, UD_VECTOR);
+	return 1;
+}
+
 static int handle_monitor_trap(struct kvm_vcpu *vcpu)
 {
 	return 1;
@@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
 	[EXIT_REASON_INVEPT]                  = handle_invept,
 	[EXIT_REASON_INVVPID]                 = handle_invvpid,
+	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
 	[EXIT_REASON_XSAVES]                  = handle_xsaves,
 	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
 	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
-- 
2.14.1.480.gb18f417b89-goog

[PATCH v2] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

A guest may not be configured to support RDSEED, even when the host
does. If the guest does not support RDSEED, intercept the instruction
and synthesize #UD.
---
 arch/x86/kvm/vmx.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ed1074e98b8e..30dac6eb4b3d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 			SECONDARY_EXEC_SHADOW_VMCS |
 			SECONDARY_EXEC_XSAVES |
+			SECONDARY_EXEC_RDSEED |
 			SECONDARY_EXEC_ENABLE_PML |
 			SECONDARY_EXEC_TSC_SCALING |
 			SECONDARY_EXEC_ENABLE_VMFUNC;
@@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 	if (!enable_pml)
 		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
 
+	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
+		exec_control &= ~SECONDARY_EXEC_RDSEED;
+
 	return exec_control;
 }
 
@@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
 	return handle_nop(vcpu);
 }
 
+static int handle_invalid_op(struct kvm_vcpu *vcpu)
+{
+	kvm_queue_exception(vcpu, UD_VECTOR);
+	return 1;
+}
+
 static int handle_monitor_trap(struct kvm_vcpu *vcpu)
 {
 	return 1;
@@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
 	[EXIT_REASON_INVEPT]                  = handle_invept,
 	[EXIT_REASON_INVVPID]                 = handle_invvpid,
+	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
 	[EXIT_REASON_XSAVES]                  = handle_xsaves,
 	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
 	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
-- 
2.14.1.480.gb18f417b89-goog

Re: [PATCH v2] kvm: vmx: Raise #UD on unsupported RDSEED

[Wanpeng Li]

2017-08-19 2:45 GMT+08:00 Jim Mattson <jmattson@google.com>:
> A guest may not be configured to support RDSEED, even when the host
> does. If the guest does not support RDSEED, intercept the instruction
> and synthesize #UD.
> ---

You miss your SOB? Otherwise, Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>

>  arch/x86/kvm/vmx.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ed1074e98b8e..30dac6eb4b3d 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>                         SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
>                         SECONDARY_EXEC_SHADOW_VMCS |
>                         SECONDARY_EXEC_XSAVES |
> +                       SECONDARY_EXEC_RDSEED |
>                         SECONDARY_EXEC_ENABLE_PML |
>                         SECONDARY_EXEC_TSC_SCALING |
>                         SECONDARY_EXEC_ENABLE_VMFUNC;
> @@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
>         if (!enable_pml)
>                 exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>
> +       if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
> +               exec_control &= ~SECONDARY_EXEC_RDSEED;
> +
>         return exec_control;
>  }
>
> @@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
>         return handle_nop(vcpu);
>  }
>
> +static int handle_invalid_op(struct kvm_vcpu *vcpu)
> +{
> +       kvm_queue_exception(vcpu, UD_VECTOR);
> +       return 1;
> +}
> +
>  static int handle_monitor_trap(struct kvm_vcpu *vcpu)
>  {
>         return 1;
> @@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>         [EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
>         [EXIT_REASON_INVEPT]                  = handle_invept,
>         [EXIT_REASON_INVVPID]                 = handle_invvpid,
> +       [EXIT_REASON_RDSEED]                  = handle_invalid_op,
>         [EXIT_REASON_XSAVES]                  = handle_xsaves,
>         [EXIT_REASON_XRSTORS]                 = handle_xrstors,
>         [EXIT_REASON_PML_FULL]                = handle_pml_full,
> --
> 2.14.1.480.gb18f417b89-goog
>

Re: [PATCH] kvm: vmx: Raise #UD on unsupported RDSEED

[David Hildenbrand]

On 18.08.2017 20:43, Jim Mattson wrote:
> A guest may not be configured to support RDSEED, even when the host
> does. If the guest does not support RDSEED, intercept the instruction
> and synthesize #UD.

Would the same also hold for nVMX guests? I think if our L1 CPU does not
have RSEED, then also the L2 CPU should not be allowed to use it.

@@ -10371,6 +10371,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12,
                                  SECONDARY_EXEC_RDTSCP |
                                  SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
                                  SECONDARY_EXEC_APIC_REGISTER_VIRT |
+                                 SECONDARY_EXEC_RDSEED_EXITING |
                                  SECONDARY_EXEC_ENABLE_VMFUNC);
                if (nested_cpu_has(vmcs12,
                                   CPU_BASED_ACTIVATE_SECONDARY_CONTROLS)) {


and maybe also


+++ b/arch/x86/kvm/vmx.c
@@ -2811,6 +2811,7 @@ static void nested_vmx_setup_ctls_msrs(struct
vcpu_vmx *vmx)
                SECONDARY_EXEC_RDRAND | SECONDARY_EXEC_RDSEED |
                SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
                SECONDARY_EXEC_RDTSCP |
+               SECONDARY_EXEC_RDSEED_EXITING |
                SECONDARY_EXEC_DESC |
                SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
                SECONDARY_EXEC_APIC_REGISTER_VIRT |

(but I always get confused about the level of filtering)

> ---
>  arch/x86/kvm/vmx.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ed1074e98b8e..8b9015f081b7 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>  			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
>  			SECONDARY_EXEC_SHADOW_VMCS |
>  			SECONDARY_EXEC_XSAVES |
> +			SECONDARY_EXEC_RDSEED_EXITING |
>  			SECONDARY_EXEC_ENABLE_PML |
>  			SECONDARY_EXEC_TSC_SCALING |
>  			SECONDARY_EXEC_ENABLE_VMFUNC;
> @@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
>  	if (!enable_pml)
>  		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>  
> +	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
> +		exec_control &= ~SECONDARY_EXEC_RDSEED_EXITING;
> +
>  	return exec_control;
>  }
>  
> @@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
>  	return handle_nop(vcpu);
>  }
>  
> +static int handle_invalid_op(struct kvm_vcpu *vcpu)
> +{
> +	kvm_queue_exception(vcpu, UD_VECTOR);
> +	return 1;
> +}
> +

(unrelated to this patch)
just wondering if we should now replace most code fragments

kvm_queue_exception(vcpu, UD_VECTOR);
return 1;

by

return handle_invalid_op(vcpu);


>  static int handle_monitor_trap(struct kvm_vcpu *vcpu)
>  {
>  	return 1;
> @@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>  	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
>  	[EXIT_REASON_INVEPT]                  = handle_invept,
>  	[EXIT_REASON_INVVPID]                 = handle_invvpid,
> +	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
>  	[EXIT_REASON_XSAVES]                  = handle_xsaves,
>  	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
>  	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
> 


-- 

Thanks,

David

Re: [PATCH] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

Right. If L1 doesn't support RDSEED, then the corresponding
"allowed-1" bit in the IA32_VMX_PROCBASED_CTLS2 MSR should be cleared.
I think vmx_cpuid_update is the right place for this. Note, however,
that prepare_vmcs02() should still respect L0's setting of this bit.

On Mon, Aug 21, 2017 at 6:00 AM, David Hildenbrand <david@redhat.com> wrote:
> On 18.08.2017 20:43, Jim Mattson wrote:
>> A guest may not be configured to support RDSEED, even when the host
>> does. If the guest does not support RDSEED, intercept the instruction
>> and synthesize #UD.
>
> Would the same also hold for nVMX guests? I think if our L1 CPU does not
> have RSEED, then also the L2 CPU should not be allowed to use it.
>
> @@ -10371,6 +10371,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu,
> struct vmcs12 *vmcs12,
>                                   SECONDARY_EXEC_RDTSCP |
>                                   SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
>                                   SECONDARY_EXEC_APIC_REGISTER_VIRT |
> +                                 SECONDARY_EXEC_RDSEED_EXITING |
>                                   SECONDARY_EXEC_ENABLE_VMFUNC);
>                 if (nested_cpu_has(vmcs12,
>                                    CPU_BASED_ACTIVATE_SECONDARY_CONTROLS)) {
>
>
> and maybe also
>
>
> +++ b/arch/x86/kvm/vmx.c
> @@ -2811,6 +2811,7 @@ static void nested_vmx_setup_ctls_msrs(struct
> vcpu_vmx *vmx)
>                 SECONDARY_EXEC_RDRAND | SECONDARY_EXEC_RDSEED |
>                 SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
>                 SECONDARY_EXEC_RDTSCP |
> +               SECONDARY_EXEC_RDSEED_EXITING |
>                 SECONDARY_EXEC_DESC |
>                 SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
>                 SECONDARY_EXEC_APIC_REGISTER_VIRT |
>
> (but I always get confused about the level of filtering)
>
>> ---
>>  arch/x86/kvm/vmx.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index ed1074e98b8e..8b9015f081b7 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>>                       SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
>>                       SECONDARY_EXEC_SHADOW_VMCS |
>>                       SECONDARY_EXEC_XSAVES |
>> +                     SECONDARY_EXEC_RDSEED_EXITING |
>>                       SECONDARY_EXEC_ENABLE_PML |
>>                       SECONDARY_EXEC_TSC_SCALING |
>>                       SECONDARY_EXEC_ENABLE_VMFUNC;
>> @@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
>>       if (!enable_pml)
>>               exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>>
>> +     if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
>> +             exec_control &= ~SECONDARY_EXEC_RDSEED_EXITING;
>> +
>>       return exec_control;
>>  }
>>
>> @@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
>>       return handle_nop(vcpu);
>>  }
>>
>> +static int handle_invalid_op(struct kvm_vcpu *vcpu)
>> +{
>> +     kvm_queue_exception(vcpu, UD_VECTOR);
>> +     return 1;
>> +}
>> +
>
> (unrelated to this patch)
> just wondering if we should now replace most code fragments
>
> kvm_queue_exception(vcpu, UD_VECTOR);
> return 1;
>
> by
>
> return handle_invalid_op(vcpu);
>
>
>>  static int handle_monitor_trap(struct kvm_vcpu *vcpu)
>>  {
>>       return 1;
>> @@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>>       [EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
>>       [EXIT_REASON_INVEPT]                  = handle_invept,
>>       [EXIT_REASON_INVVPID]                 = handle_invvpid,
>> +     [EXIT_REASON_RDSEED]                  = handle_invalid_op,
>>       [EXIT_REASON_XSAVES]                  = handle_xsaves,
>>       [EXIT_REASON_XRSTORS]                 = handle_xrstors,
>>       [EXIT_REASON_PML_FULL]                = handle_pml_full,
>>
>
>
> --
>
> Thanks,
>
> David

[PATCH v3] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

A guest may not be configured to support RDSEED, even when the host
does. If the guest does not support RDSEED, intercept the instruction
and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
in the IA32_VMX_PROCBASED_CTLS2 MSR.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/vmx.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ed1074e98b8e..482f4130c43f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 			SECONDARY_EXEC_SHADOW_VMCS |
 			SECONDARY_EXEC_XSAVES |
+			SECONDARY_EXEC_RDSEED |
 			SECONDARY_EXEC_ENABLE_PML |
 			SECONDARY_EXEC_TSC_SCALING |
 			SECONDARY_EXEC_ENABLE_VMFUNC;
@@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 	if (!enable_pml)
 		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
 
+	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
+		exec_control &= ~SECONDARY_EXEC_RDSEED;
+
 	return exec_control;
 }
 
@@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
 	return handle_nop(vcpu);
 }
 
+static int handle_invalid_op(struct kvm_vcpu *vcpu)
+{
+	kvm_queue_exception(vcpu, UD_VECTOR);
+	return 1;
+}
+
 static int handle_monitor_trap(struct kvm_vcpu *vcpu)
 {
 	return 1;
@@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
 	[EXIT_REASON_INVEPT]                  = handle_invept,
 	[EXIT_REASON_INVVPID]                 = handle_invvpid,
+	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
 	[EXIT_REASON_XSAVES]                  = handle_xsaves,
 	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
 	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
@@ -9665,6 +9676,10 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	if (!guest_cpuid_has(vcpu, X86_FEATURE_RDSEED))
+		vmx->nested.nested_vmx_secondary_ctls_high &=
+			~SECONDARY_EXEC_RDSEED;
+
 	if (cpu_has_secondary_exec_ctrls())
 		vmcs_set_secondary_exec_control(secondary_exec_ctl);
 
-- 
2.14.1.480.gb18f417b89-goog

Re: [PATCH] kvm: vmx: Raise #UD on unsupported RDSEED

[David Hildenbrand]

On 21.08.2017 18:37, Jim Mattson wrote:
> Right. If L1 doesn't support RDSEED, then the corresponding
> "allowed-1" bit in the IA32_VMX_PROCBASED_CTLS2 MSR should be cleared.
> I think vmx_cpuid_update is the right place for this. Note, however,
> that prepare_vmcs02() should still respect L0's setting of this bit.
> 

Right, now I also realize why you sent v2 (EXITING vs. !EXITING) :)


-- 

Thanks,

David

Re: [PATCH] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

Perhaps this change to vmx_cpuid_update is too simplistic, and it
should follow the pattern established for RDTSCP/INVPCID instead?

On Mon, Aug 21, 2017 at 9:50 AM, David Hildenbrand <david@redhat.com> wrote:
> On 21.08.2017 18:37, Jim Mattson wrote:
>> Right. If L1 doesn't support RDSEED, then the corresponding
>> "allowed-1" bit in the IA32_VMX_PROCBASED_CTLS2 MSR should be cleared.
>> I think vmx_cpuid_update is the right place for this. Note, however,
>> that prepare_vmcs02() should still respect L0's setting of this bit.
>>
>
> Right, now I also realize why you sent v2 (EXITING vs. !EXITING) :)
>
>
> --
>
> Thanks,
>
> David

Re: [PATCH] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

There is a potential conflict here between KVM_SET_CPUID and
KVM_SET_MSRS, if the two don't agree about the setting of the
RDSEED-exiting "allowed-1" bit in the IA32_VMX_PROCBASED_CTLS2 MSR.
But we already have that issue with the "allowed-1" bit for "enable
RDTSCP," so this is nothing new.

Surprisingly, we don't have that issue with the "allowed-1" setting
for "enable INVPCID," because vmx_cpuid_update() doesn't make any
attempt to update that bit.

On Mon, Aug 21, 2017 at 10:01 AM, Jim Mattson <jmattson@google.com> wrote:
> Perhaps this change to vmx_cpuid_update is too simplistic, and it
> should follow the pattern established for RDTSCP/INVPCID instead?
>
> On Mon, Aug 21, 2017 at 9:50 AM, David Hildenbrand <david@redhat.com> wrote:
>> On 21.08.2017 18:37, Jim Mattson wrote:
>>> Right. If L1 doesn't support RDSEED, then the corresponding
>>> "allowed-1" bit in the IA32_VMX_PROCBASED_CTLS2 MSR should be cleared.
>>> I think vmx_cpuid_update is the right place for this. Note, however,
>>> that prepare_vmcs02() should still respect L0's setting of this bit.
>>>
>>
>> Right, now I also realize why you sent v2 (EXITING vs. !EXITING) :)
>>
>>
>> --
>>
>> Thanks,
>>
>> David

[PATCH v4] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

A guest may not be configured to support RDSEED, even when the host
does. If the guest does not support RDSEED, intercept the instruction
and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
in the IA32_VMX_PROCBASED_CTLS2 MSR.

Change-Id: Iac4f3f4ef22c0d6db9f7a23cf6830aac79116ced
---
 arch/x86/kvm/vmx.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ed1074e98b8e..61174e1f7d0f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 			SECONDARY_EXEC_SHADOW_VMCS |
 			SECONDARY_EXEC_XSAVES |
+			SECONDARY_EXEC_RDSEED |
 			SECONDARY_EXEC_ENABLE_PML |
 			SECONDARY_EXEC_TSC_SCALING |
 			SECONDARY_EXEC_ENABLE_VMFUNC;
@@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 	if (!enable_pml)
 		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
 
+	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
+		exec_control &= ~SECONDARY_EXEC_RDSEED;
+
 	return exec_control;
 }
 
@@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
 	return handle_nop(vcpu);
 }
 
+static int handle_invalid_op(struct kvm_vcpu *vcpu)
+{
+	kvm_queue_exception(vcpu, UD_VECTOR);
+	return 1;
+}
+
 static int handle_monitor_trap(struct kvm_vcpu *vcpu)
 {
 	return 1;
@@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
 	[EXIT_REASON_INVEPT]                  = handle_invept,
 	[EXIT_REASON_INVVPID]                 = handle_invvpid,
+	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
 	[EXIT_REASON_XSAVES]                  = handle_xsaves,
 	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
 	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
@@ -8979,6 +8990,12 @@ static bool vmx_mpx_supported(void)
 		(vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
 }
 
+static bool vmx_rdseed_supported(void)
+{
+	return vmcs_config.cpu_based_2nd_exec_ctrl &
+		SECONDARY_EXEC_RDSEED;
+}
+
 static bool vmx_xsaves_supported(void)
 {
 	return vmcs_config.cpu_based_2nd_exec_ctrl &
@@ -9665,6 +9682,24 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	if (vmx_rdseed_supported()) {
+		bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
+
+		if (rdseed_enabled)
+			secondary_exec_ctl &= ~SECONDARY_EXEC_RDSEED;
+		else
+			secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;
+
+		if (nested) {
+			if (rdseed_enabled)
+				vmx->nested.nested_vmx_secondary_ctls_high |=
+					SECONDARY_EXEC_RDSEED;
+			else
+				vmx->nested.nested_vmx_secondary_ctls_high &=
+					~SECONDARY_EXEC_RDSEED;
+		}
+	}
+
 	if (cpu_has_secondary_exec_ctrls())
 		vmcs_set_secondary_exec_control(secondary_exec_ctl);
 
-- 
2.14.1.480.gb18f417b89-goog

[PATCH v5] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

A guest may not be configured to support RDSEED, even when the host
does. If the guest does not support RDSEED, intercept the instruction
and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
in the IA32_VMX_PROCBASED_CTLS2 MSR.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/vmx.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ed1074e98b8e..61174e1f7d0f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 			SECONDARY_EXEC_SHADOW_VMCS |
 			SECONDARY_EXEC_XSAVES |
+			SECONDARY_EXEC_RDSEED |
 			SECONDARY_EXEC_ENABLE_PML |
 			SECONDARY_EXEC_TSC_SCALING |
 			SECONDARY_EXEC_ENABLE_VMFUNC;
@@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 	if (!enable_pml)
 		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
 
+	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
+		exec_control &= ~SECONDARY_EXEC_RDSEED;
+
 	return exec_control;
 }
 
@@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
 	return handle_nop(vcpu);
 }
 
+static int handle_invalid_op(struct kvm_vcpu *vcpu)
+{
+	kvm_queue_exception(vcpu, UD_VECTOR);
+	return 1;
+}
+
 static int handle_monitor_trap(struct kvm_vcpu *vcpu)
 {
 	return 1;
@@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
 	[EXIT_REASON_INVEPT]                  = handle_invept,
 	[EXIT_REASON_INVVPID]                 = handle_invvpid,
+	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
 	[EXIT_REASON_XSAVES]                  = handle_xsaves,
 	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
 	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
@@ -8979,6 +8990,12 @@ static bool vmx_mpx_supported(void)
 		(vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
 }
 
+static bool vmx_rdseed_supported(void)
+{
+	return vmcs_config.cpu_based_2nd_exec_ctrl &
+		SECONDARY_EXEC_RDSEED;
+}
+
 static bool vmx_xsaves_supported(void)
 {
 	return vmcs_config.cpu_based_2nd_exec_ctrl &
@@ -9665,6 +9682,24 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	if (vmx_rdseed_supported()) {
+		bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
+
+		if (rdseed_enabled)
+			secondary_exec_ctl &= ~SECONDARY_EXEC_RDSEED;
+		else
+			secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;
+
+		if (nested) {
+			if (rdseed_enabled)
+				vmx->nested.nested_vmx_secondary_ctls_high |=
+					SECONDARY_EXEC_RDSEED;
+			else
+				vmx->nested.nested_vmx_secondary_ctls_high &=
+					~SECONDARY_EXEC_RDSEED;
+		}
+	}
+
 	if (cpu_has_secondary_exec_ctrls())
 		vmcs_set_secondary_exec_control(secondary_exec_ctl);
 
-- 
2.14.1.480.gb18f417b89-goog

Re: [PATCH v5] kvm: vmx: Raise #UD on unsupported RDSEED

[Radim Krčmář]

2017-08-21 12:26-0700, Jim Mattson:
> A guest may not be configured to support RDSEED, even when the host
> does. If the guest does not support RDSEED, intercept the instruction
> and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
> in the IA32_VMX_PROCBASED_CTLS2 MSR.

(RDRAND looks the same.)

> Signed-off-by: Jim Mattson <jmattson@google.com>
> ---
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> @@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
>  	if (!enable_pml)
>  		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>  
> +	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
> +		exec_control &= ~SECONDARY_EXEC_RDSEED;
> +
>  	return exec_control;
>  }
>  
> @@ -9665,6 +9682,24 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
>  		}
>  	}
>  
> +	if (vmx_rdseed_supported()) {
> +		bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
> +
> +		if (rdseed_enabled)
> +			secondary_exec_ctl &= ~SECONDARY_EXEC_RDSEED;

All other CPUID-controlled features use vmx_cpuid_update(), but I would
actually prefer to have it in vmx_secondary_exec_control.  In any case,
combining those two is weird.

> +		else
> +			secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;

The feature can never be unset here, so we can have just the first
branch,

thanks.

> +
> +		if (nested) {
> +			if (rdseed_enabled)
> +				vmx->nested.nested_vmx_secondary_ctls_high |=
> +					SECONDARY_EXEC_RDSEED;
> +			else
> +				vmx->nested.nested_vmx_secondary_ctls_high &=
> +					~SECONDARY_EXEC_RDSEED;
> +		}
> +	}

I think it would be nicer to generalize that pattern:
(We can call it after updating the MSRs too.)

---8<---
Subject: [PATCH] KVM: nVMX: refactor secondary_ctls_high updates

We should not enable a VMX feature if its instruction is not in guest
CPUID or not provided by hardware.  The change allows us to easily add
more features.

RDTSCP will always get configured with CPUID, so there is no need to set
it from the beginning, just like INVPCID.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 arch/x86/kvm/vmx.c | 46 +++++++++++++++++++++-------------------------
 1 file changed, 21 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 2b92c2de2b3a..7e2b33e0948d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2810,7 +2810,6 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
 	vmx->nested.nested_vmx_secondary_ctls_high &=
 		SECONDARY_EXEC_RDRAND | SECONDARY_EXEC_RDSEED |
 		SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
-		SECONDARY_EXEC_RDTSCP |
 		SECONDARY_EXEC_DESC |
 		SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
 		SECONDARY_EXEC_APIC_REGISTER_VIRT |
@@ -9623,25 +9622,28 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu)
 #undef cr4_fixed1_update
 }
 
+/*
+ * Update MSR_IA32_VMX_PROCBASED_CTLS2 according to CPUID.  Selected features
+ * are enabled iff they are enabled in CPUID and supported by the host.
+ */
+static void nested_vmx_secondary_ctls_high_update(struct kvm_vcpu *vcpu,
+		u32 host_secondary_exec_ctl)
+{
+	u32 mask = SECONDARY_EXEC_RDTSCP | SECONDARY_EXEC_ENABLE_INVPCID;
+
+	vcpu->vmx.nested.nested_vmx_secondary_ctls_high &= ~mask
+	vcpu->vmx.nested.nested_vmx_secondary_ctls_high |=
+			host_secondary_exec_ctl & mask;
+}
+
 static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
 	u32 secondary_exec_ctl = vmx_secondary_exec_control(vmx);
 
-	if (vmx_rdtscp_supported()) {
-		bool rdtscp_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP);
-		if (!rdtscp_enabled)
-			secondary_exec_ctl &= ~SECONDARY_EXEC_RDTSCP;
-
-		if (nested) {
-			if (rdtscp_enabled)
-				vmx->nested.nested_vmx_secondary_ctls_high |=
-					SECONDARY_EXEC_RDTSCP;
-			else
-				vmx->nested.nested_vmx_secondary_ctls_high &=
-					~SECONDARY_EXEC_RDTSCP;
-		}
-	}
+	if (vmx_rdtscp_supported() &&
+	    !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
+		secondary_exec_ctl &= ~SECONDARY_EXEC_RDTSCP;
 
 	if (vmx_invpcid_supported()) {
 		/* Exposing INVPCID only when PCID is exposed */
@@ -9653,15 +9655,6 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 			secondary_exec_ctl &= ~SECONDARY_EXEC_ENABLE_INVPCID;
 			guest_cpuid_clear(vcpu, X86_FEATURE_INVPCID);
 		}
-
-		if (nested) {
-			if (invpcid_enabled)
-				vmx->nested.nested_vmx_secondary_ctls_high |=
-					SECONDARY_EXEC_ENABLE_INVPCID;
-			else
-				vmx->nested.nested_vmx_secondary_ctls_high &=
-					~SECONDARY_EXEC_ENABLE_INVPCID;
-		}
 	}
 
 	if (cpu_has_secondary_exec_ctrls())
@@ -9674,8 +9667,11 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 		to_vmx(vcpu)->msr_ia32_feature_control_valid_bits &=
 			~FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
 
-	if (nested_vmx_allowed(vcpu))
+	if (nested_vmx_allowed(vcpu)) {
 		nested_vmx_cr_fixed1_bits_update(vcpu);
+		nested_vmx_secondary_ctls_high_update(vcpu, secondary_exec_ctl);
+	}
+
 }
 
 static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
-- 
2.13.3

Re: [PATCH v5] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

On Mon, Aug 21, 2017 at 1:32 PM, Radim Krčmář <rkrcmar@redhat.com> wrote:
> 2017-08-21 12:26-0700, Jim Mattson:
>> A guest may not be configured to support RDSEED, even when the host
>> does. If the guest does not support RDSEED, intercept the instruction
>> and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
>> in the IA32_VMX_PROCBASED_CTLS2 MSR.
>
> (RDRAND looks the same.)

Agreed. A general paradigm would be nicer.

>
>> Signed-off-by: Jim Mattson <jmattson@google.com>
>> ---
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> @@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
>>       if (!enable_pml)
>>               exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>>
>> +     if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
>> +             exec_control &= ~SECONDARY_EXEC_RDSEED;
>> +
>>       return exec_control;
>>  }
>>
>> @@ -9665,6 +9682,24 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
>>               }
>>       }
>>
>> +     if (vmx_rdseed_supported()) {
>> +             bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
>> +
>> +             if (rdseed_enabled)
>> +                     secondary_exec_ctl &= ~SECONDARY_EXEC_RDSEED;
>
> All other CPUID-controlled features use vmx_cpuid_update(), but I would
> actually prefer to have it in vmx_secondary_exec_control.  In any case,
> combining those two is weird.

Yes, it is weird. The reasons I adopted this two-pronged approach are:
1. vmx_secondary_exec_control() is only used at VCPU creation time to
set the default controls for the vmcs01.
2. Changes due to KVM_SET_CPUID2 are pushed into the vmcs01 by
vmx_cpuid_update() [assuming that the vcpu is not in virtualized vmx
non-root mode when the ioctl is called].
3. vmx_secondary_exec_control() is used at every emulated VM-entry
from L1 to L2 to determine the controls that L0 needs to set in the
vmcs02.

Ideally, vmx_secondary_exec_control() would always return the
secondary processor-based execution controls for vmcs01, but too many
changes are already being made behind its back.

>
>> +             else
>> +                     secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;
>
> The feature can never be unset here, so we can have just the first
> branch,

I believe that CPUID.07H:EBX.RDSEED can be unset by
KVM_SET_CPUID/KVM_SET_CPUID2 (and both ioctls pass through here). How
else would you defeature a VCPU?

> thanks.
>
>> +
>> +             if (nested) {
>> +                     if (rdseed_enabled)
>> +                             vmx->nested.nested_vmx_secondary_ctls_high |=
>> +                                     SECONDARY_EXEC_RDSEED;

Arguably, this isn't necessary. A sane platform could have support for
the RDSEED instruction without support for "RDSEED exiting." The same
applies to INVPCID, in the code above.

>> +                     else
>> +                             vmx->nested.nested_vmx_secondary_ctls_high &=
>> +                                     ~SECONDARY_EXEC_RDSEED;
>> +             }
>> +     }
>
> I think it would be nicer to generalize that pattern:

In general, "<opcode> exiting" or enable <opcode>" VMX capabilities
should be forced off if the CPUID feature bit for the opcode is
cleared (except, perhaps, for the MONITOR/MWAIT oddity).

> (We can call it after updating the MSRs too.)

After updating the MSRs, perhaps the CPUID feature bit for the opcode
should be forced on if the corresponding "allowed-1" VMX capability
bit is set. Or, perhaps it should be an error to set the VMX
capability bit via KVM_SET_MSRS after having already cleared the
corresponding CPUID feature bit via KVM_SET_CPUID2.

>
> ---8<---
> Subject: [PATCH] KVM: nVMX: refactor secondary_ctls_high updates
>
> We should not enable a VMX feature if its instruction is not in guest
> CPUID or not provided by hardware.  The change allows us to easily add
> more features.
>
> RDTSCP will always get configured with CPUID, so there is no need to set
> it from the beginning, just like INVPCID.

Isn't RDTSCP automatically set in the default CPUID if there is
hardware support for "enable RDTSCP"? When the default CPUID is used,
there is no call to kvm_x86_ops->cpuid_update. Shouldn't the default
VMX capability MSRs match the default CPUID settings?

>
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
>  arch/x86/kvm/vmx.c | 46 +++++++++++++++++++++-------------------------
>  1 file changed, 21 insertions(+), 25 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 2b92c2de2b3a..7e2b33e0948d 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2810,7 +2810,6 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
>         vmx->nested.nested_vmx_secondary_ctls_high &=
>                 SECONDARY_EXEC_RDRAND | SECONDARY_EXEC_RDSEED |
>                 SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
> -               SECONDARY_EXEC_RDTSCP |
>                 SECONDARY_EXEC_DESC |
>                 SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
>                 SECONDARY_EXEC_APIC_REGISTER_VIRT |
> @@ -9623,25 +9622,28 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu)
>  #undef cr4_fixed1_update
>  }
>
> +/*
> + * Update MSR_IA32_VMX_PROCBASED_CTLS2 according to CPUID.  Selected features
> + * are enabled iff they are enabled in CPUID and supported by the host.
> + */
> +static void nested_vmx_secondary_ctls_high_update(struct kvm_vcpu *vcpu,
> +               u32 host_secondary_exec_ctl)
> +{
> +       u32 mask = SECONDARY_EXEC_RDTSCP | SECONDARY_EXEC_ENABLE_INVPCID;
> +
> +       vcpu->vmx.nested.nested_vmx_secondary_ctls_high &= ~mask
> +       vcpu->vmx.nested.nested_vmx_secondary_ctls_high |=
> +                       host_secondary_exec_ctl & mask;
> +}
> +
>  static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
>  {
>         struct vcpu_vmx *vmx = to_vmx(vcpu);
>         u32 secondary_exec_ctl = vmx_secondary_exec_control(vmx);
>
> -       if (vmx_rdtscp_supported()) {
> -               bool rdtscp_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP);
> -               if (!rdtscp_enabled)
> -                       secondary_exec_ctl &= ~SECONDARY_EXEC_RDTSCP;
> -
> -               if (nested) {
> -                       if (rdtscp_enabled)
> -                               vmx->nested.nested_vmx_secondary_ctls_high |=
> -                                       SECONDARY_EXEC_RDTSCP;
> -                       else
> -                               vmx->nested.nested_vmx_secondary_ctls_high &=
> -                                       ~SECONDARY_EXEC_RDTSCP;
> -               }
> -       }
> +       if (vmx_rdtscp_supported() &&
> +           !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
> +               secondary_exec_ctl &= ~SECONDARY_EXEC_RDTSCP;
>
>         if (vmx_invpcid_supported()) {
>                 /* Exposing INVPCID only when PCID is exposed */
> @@ -9653,15 +9655,6 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
>                         secondary_exec_ctl &= ~SECONDARY_EXEC_ENABLE_INVPCID;
>                         guest_cpuid_clear(vcpu, X86_FEATURE_INVPCID);
>                 }
> -
> -               if (nested) {
> -                       if (invpcid_enabled)
> -                               vmx->nested.nested_vmx_secondary_ctls_high |=
> -                                       SECONDARY_EXEC_ENABLE_INVPCID;
> -                       else
> -                               vmx->nested.nested_vmx_secondary_ctls_high &=
> -                                       ~SECONDARY_EXEC_ENABLE_INVPCID;
> -               }
>         }
>
>         if (cpu_has_secondary_exec_ctrls())
> @@ -9674,8 +9667,11 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
>                 to_vmx(vcpu)->msr_ia32_feature_control_valid_bits &=
>                         ~FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
>
> -       if (nested_vmx_allowed(vcpu))
> +       if (nested_vmx_allowed(vcpu)) {
>                 nested_vmx_cr_fixed1_bits_update(vcpu);
> +               nested_vmx_secondary_ctls_high_update(vcpu, secondary_exec_ctl);
> +       }
> +
>  }
>
>  static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
> --
> 2.13.3
>

Re: [PATCH v5] kvm: vmx: Raise #UD on unsupported RDSEED

[David Hildenbrand]

On 21.08.2017 21:26, Jim Mattson wrote:
> A guest may not be configured to support RDSEED, even when the host
> does. If the guest does not support RDSEED, intercept the instruction
> and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
> in the IA32_VMX_PROCBASED_CTLS2 MSR.
> 
> Signed-off-by: Jim Mattson <jmattson@google.com>

I'd really vote to update

SECONDARY_EXEC_RDSEED -> SECONDARY_EXEC_RDSEED_EXITING
SECONDARY_EXEC_RDRAND -> SECONDARY_EXEC_RDRAND_EXITING

Otherwise this looks like it would enable RDSEED interpretation. And
this way it matches the SDM definition.

-- 

Thanks,

David

Re: [PATCH v5] kvm: vmx: Raise #UD on unsupported RDSEED

[David Hildenbrand]

>>
>>> +
>>> +             if (nested) {
>>> +                     if (rdseed_enabled)
>>> +                             vmx->nested.nested_vmx_secondary_ctls_high |=
>>> +                                     SECONDARY_EXEC_RDSEED;
> 
> Arguably, this isn't necessary. A sane platform could have support for
> the RDSEED instruction without support for "RDSEED exiting." The same
> applies to INVPCID, in the code above.

I agree. It should be handled like this:

Host has RDSEED but L1 does not (via CPUID):
a) If RDSEED_EXITING is available, enable it (to fake absence)
b) If RDSEED_EXITING is available, enable it in vmcs02 (to fake absence)
b) Forbid RDSEED_EXITING for L1->L2 (in vmcs12) and via MSR

Host and L1 have RDSEED:
a) Don't set RDSEED_EXITING
b) Allow RDSEED_EXITING for L1->L2 (in vmcs12) and via MSR (if
   available)

Neither has RDSEED:
a) Don't set RDSEED_EXITING
b) Forbid RDSEED_EXITING for L1->L2 (in vmcs12) and via MSR

I wonder if we would have to take care about !RDSEED but RDSEED_EXITING
(could be created in nested setups, right?)

> 
>>> +                     else
>>> +                             vmx->nested.nested_vmx_secondary_ctls_high &=
>>> +                                     ~SECONDARY_EXEC_RDSEED;
>>> +             }
>>> +     }
>>
>> I think it would be nicer to generalize that pattern:
> 
> In general, "<opcode> exiting" or enable <opcode>" VMX capabilities
> should be forced off if the CPUID feature bit for the opcode is
> cleared (except, perhaps, for the MONITOR/MWAIT oddity).

Yes, I agree.

> 
>> (We can call it after updating the MSRs too.)
> 
> After updating the MSRs, perhaps the CPUID feature bit for the opcode
> should be forced on if the corresponding "allowed-1" VMX capability
> bit is set. Or, perhaps it should be an error to set the VMX
> capability bit via KVM_SET_MSRS after having already cleared the
> corresponding CPUID feature bit via KVM_SET_CPUID2.

I prefer the latter (implicit enabling sounds strange), if that doesn't
result in any other conflicts.

-- 

Thanks,

David

Re: [PATCH v5] kvm: vmx: Raise #UD on unsupported RDSEED

[Paolo Bonzini]

On 21/08/2017 21:26, Jim Mattson wrote:
> A guest may not be configured to support RDSEED, even when the host
> does. If the guest does not support RDSEED, intercept the instruction
> and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
> in the IA32_VMX_PROCBASED_CTLS2 MSR.
> 
> Signed-off-by: Jim Mattson <jmattson@google.com>

Usually we're not that particular about #UD-ing on disabled instructions
(because you cannot do it for all instructions), but in this case I
agree that we should do it for the sake of getting vmexits right.

I'm applying v5 and posting shortly a similar patch for RDRAND.

Paolo

> ---
>  arch/x86/kvm/vmx.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ed1074e98b8e..61174e1f7d0f 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>  			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
>  			SECONDARY_EXEC_SHADOW_VMCS |
>  			SECONDARY_EXEC_XSAVES |
> +			SECONDARY_EXEC_RDSEED |
>  			SECONDARY_EXEC_ENABLE_PML |
>  			SECONDARY_EXEC_TSC_SCALING |
>  			SECONDARY_EXEC_ENABLE_VMFUNC;
> @@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
>  	if (!enable_pml)
>  		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>  
> +	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
> +		exec_control &= ~SECONDARY_EXEC_RDSEED;
> +
>  	return exec_control;
>  }
>  
> @@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
>  	return handle_nop(vcpu);
>  }
>  
> +static int handle_invalid_op(struct kvm_vcpu *vcpu)
> +{
> +	kvm_queue_exception(vcpu, UD_VECTOR);
> +	return 1;
> +}
> +
>  static int handle_monitor_trap(struct kvm_vcpu *vcpu)
>  {
>  	return 1;
> @@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>  	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
>  	[EXIT_REASON_INVEPT]                  = handle_invept,
>  	[EXIT_REASON_INVVPID]                 = handle_invvpid,
> +	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
>  	[EXIT_REASON_XSAVES]                  = handle_xsaves,
>  	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
>  	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
> @@ -8979,6 +8990,12 @@ static bool vmx_mpx_supported(void)
>  		(vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
>  }
>  
> +static bool vmx_rdseed_supported(void)
> +{
> +	return vmcs_config.cpu_based_2nd_exec_ctrl &
> +		SECONDARY_EXEC_RDSEED;
> +}
> +
>  static bool vmx_xsaves_supported(void)
>  {
>  	return vmcs_config.cpu_based_2nd_exec_ctrl &
> @@ -9665,6 +9682,24 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
>  		}
>  	}
>  
> +	if (vmx_rdseed_supported()) {
> +		bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
> +
> +		if (rdseed_enabled)
> +			secondary_exec_ctl &= ~SECONDARY_EXEC_RDSEED;
> +		else
> +			secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;
> +
> +		if (nested) {
> +			if (rdseed_enabled)
> +				vmx->nested.nested_vmx_secondary_ctls_high |=
> +					SECONDARY_EXEC_RDSEED;
> +			else
> +				vmx->nested.nested_vmx_secondary_ctls_high &=
> +					~SECONDARY_EXEC_RDSEED;
> +		}
> +	}
> +
>  	if (cpu_has_secondary_exec_ctrls())
>  		vmcs_set_secondary_exec_control(secondary_exec_ctl);
>  
> 

Re: [PATCH v5] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

Wait, wait! I have v6 almost ready!

On Wed, Aug 23, 2017 at 2:34 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 21/08/2017 21:26, Jim Mattson wrote:
>> A guest may not be configured to support RDSEED, even when the host
>> does. If the guest does not support RDSEED, intercept the instruction
>> and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
>> in the IA32_VMX_PROCBASED_CTLS2 MSR.
>>
>> Signed-off-by: Jim Mattson <jmattson@google.com>
>
> Usually we're not that particular about #UD-ing on disabled instructions
> (because you cannot do it for all instructions), but in this case I
> agree that we should do it for the sake of getting vmexits right.
>
> I'm applying v5 and posting shortly a similar patch for RDRAND.
>
> Paolo
>
>> ---
>>  arch/x86/kvm/vmx.c | 35 +++++++++++++++++++++++++++++++++++
>>  1 file changed, 35 insertions(+)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index ed1074e98b8e..61174e1f7d0f 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -3662,6 +3662,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
>>                       SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
>>                       SECONDARY_EXEC_SHADOW_VMCS |
>>                       SECONDARY_EXEC_XSAVES |
>> +                     SECONDARY_EXEC_RDSEED |
>>                       SECONDARY_EXEC_ENABLE_PML |
>>                       SECONDARY_EXEC_TSC_SCALING |
>>                       SECONDARY_EXEC_ENABLE_VMFUNC;
>> @@ -5298,6 +5299,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
>>       if (!enable_pml)
>>               exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
>>
>> +     if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
>> +             exec_control &= ~SECONDARY_EXEC_RDSEED;
>> +
>>       return exec_control;
>>  }
>>
>> @@ -6806,6 +6810,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
>>       return handle_nop(vcpu);
>>  }
>>
>> +static int handle_invalid_op(struct kvm_vcpu *vcpu)
>> +{
>> +     kvm_queue_exception(vcpu, UD_VECTOR);
>> +     return 1;
>> +}
>> +
>>  static int handle_monitor_trap(struct kvm_vcpu *vcpu)
>>  {
>>       return 1;
>> @@ -8050,6 +8060,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
>>       [EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
>>       [EXIT_REASON_INVEPT]                  = handle_invept,
>>       [EXIT_REASON_INVVPID]                 = handle_invvpid,
>> +     [EXIT_REASON_RDSEED]                  = handle_invalid_op,
>>       [EXIT_REASON_XSAVES]                  = handle_xsaves,
>>       [EXIT_REASON_XRSTORS]                 = handle_xrstors,
>>       [EXIT_REASON_PML_FULL]                = handle_pml_full,
>> @@ -8979,6 +8990,12 @@ static bool vmx_mpx_supported(void)
>>               (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
>>  }
>>
>> +static bool vmx_rdseed_supported(void)
>> +{
>> +     return vmcs_config.cpu_based_2nd_exec_ctrl &
>> +             SECONDARY_EXEC_RDSEED;
>> +}
>> +
>>  static bool vmx_xsaves_supported(void)
>>  {
>>       return vmcs_config.cpu_based_2nd_exec_ctrl &
>> @@ -9665,6 +9682,24 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
>>               }
>>       }
>>
>> +     if (vmx_rdseed_supported()) {
>> +             bool rdseed_enabled = guest_cpuid_has(vcpu, X86_FEATURE_RDSEED);
>> +
>> +             if (rdseed_enabled)
>> +                     secondary_exec_ctl &= ~SECONDARY_EXEC_RDSEED;
>> +             else
>> +                     secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;
>> +
>> +             if (nested) {
>> +                     if (rdseed_enabled)
>> +                             vmx->nested.nested_vmx_secondary_ctls_high |=
>> +                                     SECONDARY_EXEC_RDSEED;
>> +                     else
>> +                             vmx->nested.nested_vmx_secondary_ctls_high &=
>> +                                     ~SECONDARY_EXEC_RDSEED;
>> +             }
>> +     }
>> +
>>       if (cpu_has_secondary_exec_ctrls())
>>               vmcs_set_secondary_exec_control(secondary_exec_ctl);
>>
>>
>

[PATCH v6 1/2] kvm: vmx: Raise #UD on unsupported RDSEED

[Jim Mattson]

A guest may not be configured to support RDSEED, even when the host
does. If the guest does not support RDSEED, intercept the instruction
and synthesize #UD. Also clear the "allowed-1" bit for RDSEED exiting
in the IA32_VMX_PROCBASED_CTLS2 MSR.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/vmx.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 19aa69af7c2d..9dd8637c3392 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3667,6 +3667,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 			SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 			SECONDARY_EXEC_SHADOW_VMCS |
 			SECONDARY_EXEC_XSAVES |
+			SECONDARY_EXEC_RDSEED |
 			SECONDARY_EXEC_ENABLE_PML |
 			SECONDARY_EXEC_TSC_SCALING |
 			SECONDARY_EXEC_ENABLE_VMFUNC;
@@ -5300,6 +5301,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 	if (!enable_pml)
 		exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
 
+	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
+		exec_control &= ~SECONDARY_EXEC_RDSEED;
+
 	return exec_control;
 }
 
@@ -6804,6 +6808,12 @@ static int handle_mwait(struct kvm_vcpu *vcpu)
 	return handle_nop(vcpu);
 }
 
+static int handle_invalid_op(struct kvm_vcpu *vcpu)
+{
+	kvm_queue_exception(vcpu, UD_VECTOR);
+	return 1;
+}
+
 static int handle_monitor_trap(struct kvm_vcpu *vcpu)
 {
 	return 1;
@@ -8047,6 +8057,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_MONITOR_INSTRUCTION]     = handle_monitor,
 	[EXIT_REASON_INVEPT]                  = handle_invept,
 	[EXIT_REASON_INVVPID]                 = handle_invvpid,
+	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
 	[EXIT_REASON_XSAVES]                  = handle_xsaves,
 	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
 	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
@@ -8975,6 +8986,12 @@ static bool vmx_mpx_supported(void)
 		(vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
 }
 
+static bool vmx_rdseed_supported(void)
+{
+	return vmcs_config.cpu_based_2nd_exec_ctrl &
+		SECONDARY_EXEC_RDSEED;
+}
+
 static bool vmx_xsaves_supported(void)
 {
 	return vmcs_config.cpu_based_2nd_exec_ctrl &
@@ -9620,6 +9637,12 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu)
 #undef cr4_fixed1_update
 }
 
+static void nested_vmx_secondary_ctrls_clear(struct kvm_vcpu *vcpu, u32 mask)
+{
+	if (nested)
+		to_vmx(vcpu)->nested.nested_vmx_secondary_ctls_high &= ~mask;
+}
+
 static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -9661,6 +9684,12 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	if (vmx_rdseed_supported() &&
+	    !guest_cpuid_has(vcpu, X86_FEATURE_RDSEED)) {
+		nested_vmx_secondary_ctrls_clear(vcpu, SECONDARY_EXEC_RDSEED);
+		secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;
+	}
+
 	if (cpu_has_secondary_exec_ctrls())
 		vmcs_set_secondary_exec_control(secondary_exec_ctl);
 
-- 
2.14.1.342.g6490525c54-goog

[PATCH v6 2/2] kvm: vmx: Raise #UD on unsupported RDRAND

[Jim Mattson]

A guest may not be configured to support RDRAND, even when the host
does. If the guest does not support RDRAND, intercept the instruction
and synthesize #UD. Also clear the "allowed-1" bit for RDRAND exiting
in the IA32_VMX_PROCBASED_CTLS2 MSR.

Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/vmx.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9dd8637c3392..1d59806b315b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3668,6 +3668,7 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
 			SECONDARY_EXEC_SHADOW_VMCS |
 			SECONDARY_EXEC_XSAVES |
 			SECONDARY_EXEC_RDSEED |
+			SECONDARY_EXEC_RDRAND |
 			SECONDARY_EXEC_ENABLE_PML |
 			SECONDARY_EXEC_TSC_SCALING |
 			SECONDARY_EXEC_ENABLE_VMFUNC;
@@ -5304,6 +5305,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
 	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDSEED))
 		exec_control &= ~SECONDARY_EXEC_RDSEED;
 
+	if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDRAND))
+		exec_control &= ~SECONDARY_EXEC_RDRAND;
+
 	return exec_control;
 }
 
@@ -8058,6 +8062,7 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_INVEPT]                  = handle_invept,
 	[EXIT_REASON_INVVPID]                 = handle_invvpid,
 	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
+	[EXIT_REASON_RDRAND]                  = handle_invalid_op,
 	[EXIT_REASON_XSAVES]                  = handle_xsaves,
 	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
 	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
@@ -8992,6 +8997,12 @@ static bool vmx_rdseed_supported(void)
 		SECONDARY_EXEC_RDSEED;
 }
 
+static bool vmx_rdrand_supported(void)
+{
+	return vmcs_config.cpu_based_2nd_exec_ctrl &
+		SECONDARY_EXEC_RDRAND;
+}
+
 static bool vmx_xsaves_supported(void)
 {
 	return vmcs_config.cpu_based_2nd_exec_ctrl &
@@ -9690,6 +9701,12 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 		secondary_exec_ctl |= SECONDARY_EXEC_RDSEED;
 	}
 
+	if (vmx_rdrand_supported() &&
+	    !guest_cpuid_has(vcpu, X86_FEATURE_RDRAND)) {
+		nested_vmx_secondary_ctrls_clear(vcpu, SECONDARY_EXEC_RDRAND);
+		secondary_exec_ctl |= SECONDARY_EXEC_RDRAND;
+	}
+
 	if (cpu_has_secondary_exec_ctrls())
 		vmcs_set_secondary_exec_control(secondary_exec_ctl);
 
-- 
2.14.1.342.g6490525c54-goog